Certainly finding a surrogate Dam is preferable both for nutrition and care, this is not always possible. There are several ways to go with milk replacer so I'll identify the possibilities. First we have fully constituted replacer - usually comes in a coke can size. This is very expensive, but is easy and I always have one can on hand for puppy or Dam if needed in a pinch. Wal-mart carries it in the States (so maybe TESCO for the UK??) for the best price, though you can get other brands at pet stores for a bit more. Then we have the powdered formulas which you purchase and reconstitute with sterile water. Finally, we have homemade recipes that are designed to closely replicate the dietary needs of a canine, but are not lab sciences like the first two methods are.
Canned, ready to use - This would be my plan for an orphan litter for the first week or so. Very pricey, but your sanity will be much happier not having to mix.
Powdered - Much better for the long haul when you need replacer for 4 weeks or so. Still quite expensive, but the best economical match for the task.
The Recipe - not my own, but I have used it in older puppies after we got off the powdered and while I was still weaning. If you lived far away from a source of canned or powdered - this may be your only hope.
***Warnings: Only feed a puppy whose rectal temperature is 95 degrees F or warmer. Only use sterile water and sterile equipment. Carefully monitor weight gain of puppies. No cows milk - this will give a puppy scowers. Just as you must feed an orphan litter, you must also assist them in urination and defication until they are 3+ weeks old. Never bottle feed a puppy in the 'baby cradling' position. They MUST be on THEIR tummies on a surface (your lap) with their heads pointed upward - they will choke otherwise.
Supplies: Newborn type baby bottles with pre-punctured holes. (Do not use pet nursers that you have to poke the hole in - you'll never get it right!) Mixing Bowl, whisk, Sealed jug-type container for the Recipe. Ingredients: Karo clear syrup, whole fat plain yogurt, fresh egg yolks, evaporated milk (NOT sweetened condensed) or whole goat's milk, and sterile water.
The Recipe: 10oz of Evaporated milk
1 raw egg YOLK only - no whites
3 oz sterile water (if using 10oz of whole goat - no water needed)
1/2 - 1 tsp Karo syrup - DO NOT SUBSTITUTE HONEY
1 cup WHOLE fat yogurt
Mix with whisk only - no blenders. This will keep for 24 hours so mix batches accordingly. This is a money saver and more readily available sometimes than commercial options. It has not been evaluated for nutritional content - so AS ALWAYS seek the advice of your Vet for dietary issues.
I won't go into tube feeding, though some breeders like it as it is a faster method of feeding a whole litter. If you go down the wrong tube - you will have drowned your puppy though, so its too scary for me to contemplate.
A general guideline for volume amounts for puppies (depends upon the breed size), but generally is 1 cc per ounce of weight every three hours. There are tables and charts galore on the internet as well as guidelines on the formula mixes that I would defer to as being more scientific. You basically need to weigh your puppy and establish the overall need for intake of the day divided by the number of feedings you will do per day. Younger puppies (1 -5 days old) sadly need to be fed every two hours. At 5+ days you can go to three hours and at 10+ you can go to four hours. There will not be a lot of sleep for you so when a kindly neighbor offers to help - take it!!!
Just a couple of examples of weights to Day Volumes:
8oz puppy needs 60cc/day
12oz needs 90cc/day
20oz needs 150cc/day
28oz needs 210cc/day
36oz needs 270cc/day and so on.
It depends on the age/size of the baby to determine the amount per feeding. An example would be a smaller Golden Retriever baby weighing 12oz at birth. They need 90cc /24 hours and must be fed every two hours. That's 12 feedings at 7.5 cc per feeding. You know you are doing well by measuring puppies daily and making sure they are gaining.
Lastly, if you are in the position of hand feeding an entire litter of puppies - I can assure you it will seem like an impossible task. You will need help because it will take perhaps an hour to feed (and urinate/deficate) the litter and they eat every two. Accept help. I'm not good about this, but it saved my sanity. There is a point (at 3 am probably by the third night) where you will just think you can't do it any more. I promise you will survive the sleep deprivation. It may take a while, but just chew off a day at a time. If someone will do your puppy laundry for you - let them. If someone wants to cook a meal for you - thanks a lot! You will need help, but the babies will be your reward. I was the Momma of my litter. Not the human who came in and loved them, I was the MOMMA. They loved me and you knew it when you looked in their eyes or when I sat in their pen. This was my reward.