So that leaves me with some other essentials for riding. But for these, I want best bang for buck. Can anyone recommend any specific..
Gloves
Glasses/Goggles/Lenses (whatever they are classed as)
Hydration backpack
Multitool
Puncture kit
Jacket
Pants/shorts.
Thanks guys
Quite a lot of this is really personal stuff, but here's my take.
Will you be winter riding? You can't skimp on gloves if you do, warm gloves are just a requirement for when the temperature gets down towards freezing. But other than that, there are millions out there and most of them work. I ride in motorbike gloves personally, the summer ones are armoured but also well vented, and the winter ones are very warm. My mates think I'm weird though. I might get a pair of proper bike mitts at some point. I tend not to ride in really hot weather though, it's horrible generally.
Goggles... Full on goggles are usually overkill, sunglasses should be sufficient for most use. Ones with different lenses help, there's a DHB pair from Wiggle at £35 with a clear, dark and yellow lens that always get good reviews. I don't actually wear glasses/goggles, I like moto-x style mudguards instead, but again, my mates think I'm weird.
Hydration pack- Cyclestore can do you a Camelback Chaos for £42, it's not cheap but it's very good and that's an excellent price. Love mine. You can go cheaper, my previous riding bag/hydration thing was a £5 rucksack with a bottle of water in it

Camelbak is NOT a requirement, it's just convenient. Or you can get a platypus hydration pack for about £8 and add it to any rucksack.
Multitool- buy cheap, buy twice. Topeak Alien 2 is the multitool, for me, it's awesome. MBUK might still be giving away Specialized EMT Comps, they're good too. If you do decide to buy cheap, buy really cheap, no sense in going halfway. Tescos... They're awful tools but they're better than nothing, and then get a real one later.
Puncture kit- any decently strong levers, and Park Tools patches, for me. Not a big expense but good patches are worth it. Get some spare tubes, Tesco sell perfectly decent MTB tubes for about £2. I always carry at least one tube as well as patches, for those times when I just can't be bothered to mend a puncture.
Jacket- check your local LIDL, their riding shirt and winter jacket are spot on.
Shorts- any old shorts will do frankly, you don't sweat that much through your thighs

I do have a nice pair of Alturas now but before that I was just wearing normal cargo shorts, they were fine. You don't need to be very choosy on shorts.