Agreed there's not much need for any attachments to start with. There are already a few guides here on the forums I'd recommend searching for and reading, they're really useful for beginners and I wish I'd seen them before I started.
I'd say get some camo clothing first. Any surplus stuff should be cheap (especially DPM) and clothing is quality as you'd expect. If you've got a generous budget you could search more for some different camouflage patterns and manufacturers but generally surplus is a good choice.
After that, decent pair of boots are a worthwhile purchase. Of course don't forget good eye protection too, you don't want to lose your sight so buy a well known brand. Personally I'd aim to get some ballistic goggles such as ESS Wolf Spider / Desert Locusts / Smith Optics Boogie Regulators or custom mesh products by Heroshark. Again, I think there are probably guides on eyewear anyway (if not, might make one myself)
In terms of plate carriers, cheapest you will probably get are either MFH or Condor. Both brands should be available from Military 1st. I don't think MFH is great quality, Condor is okay but not the best and will probably break after a while. There's also Flyye which are a Chinese company but their products are nice quality. However I think the cheapest plate carrier is the Fast Attack Plate Carrier for £70.
For another £30 you could get a Warrior Assault Systems DCS Plate Carrier (CKinnerly on here did a review of one) for £105-£110 which is an excellent real steel mil-spec (military quality) system (and it's available in a load of camos to suit your loadout) available from UK Tactical.
Chest rigs. Loads of choice, depending on budget. Bulle rigs are good (I have the MOLLE Recon Chest Harness) you can buy them from Flecktarn.co.uk. Condor ones are also pretty cheap (not sure how they compare to Bulle) There's also the Tactical Tailor Mini MAV which is very small but awesome for a lightweight loadout and just carrying essential sort of stuff.
If you're after gloves, Mechanix are supposed to be excellent. I'm buying a pair soon but haven't used any yet.
Hope I covered some things you were wanting to know and that it helps. Sorry for long post, I can post some links as well later if needed or you want some more inspiration or something.