you #10 should get through anything, its very short, too short even!
so if there is a problem with the blade or clippers contact the people who you bought it off.
if you are going to look after your oes yourself, take a deep breath and have a bottle of something strong waiting for AFTER!
dont expect to have a perfectly clipped dog in a couple of hours, maybe in a few days! dont try and do it in one go allow yourself a few days because you are learning. also when you clip your dog ALWAYS go in the direction of the hair, going agaist the grain cuts it half as short.
you can also use steel comb attachments that are used onto of the #10 blade that make it an inch. these just clip onto your blades. also make sure your blades are ment to be for a dog, they are different from human ones.
Blade Combs : Animal Grooming Supplies UK : Technogroom
but they only work if there are NO matts. do you have matt breaker and a good slicker and pin brush? i also would recomend a good dematting spray like show seasons, which can be used wet or dry.
also watch your blade doesnt get hot, it will burn your dog. make sure you keep oiling it too.
when brushing you need to get right down to the skin and line brush him. this should take hours!
please pm me if you want any more information, i am a dog groomer and i also have an old english too.
good luck!!!