The Pro-peak is a pretty good charger provided you're going to be sticking to fairly small models for a while. On larger batteries you'll soon start to feel the 3A limit.
Overlander.co.uk is about the easiest place to get batteries in the UK though not really the cheapest. They have a fairly good range. For cheaper you have to decide exactly what you want and then find the right supplier. The smaller suppliers tend only to sell a limited range of batteries.
BTW if you fill in the "Location" entry in your details (MyRcGroups/EditProfile then look under Additional Information) you won't need to keep saying you're from the UK
. Lots of us are you know.