For tools, if you wanted a full kit you could get a half decent one fairly cheaply (30 to 40 pounds) from Argos, I've got one of their Guild kits and it's not bad at all. The downside is that it isn't bike specific and will be missing a couple of bits you need, and you might not use half the items... I think I've used about 8 of the items in mine. What many amateur mechanics do is to start with a few really commonly used tools and later add in each tool IF they need it. The economics of one over the other is up for debate. What most people are agreed on is to avoid the very cheapest tools (that might last one job before bending or stripping), and try to get the best tool you can afford.
I'd start with:
A good multitool.
A track pump (they're very good for home use but you'll want a mini pump for when you're out).
Tyre levers
A good set of allen keys.
Couple of appropriately sized screwdrivers - depending on your bike fittings. (Check the heads though, you might have all / nearly all allen bolts).
Later you can add others, I've found good wire cutters and a decent pedal spanner to be my most useful additions.