I don't want to sound too disrespectful, Flex, but you don't need another gun for a while- and you definitely don't need to spend £300-£400 on one until you get a UKARA or similar registration.
Focus on accumulating kit such as:
A decent pair of boots
Facial protection
Magazines and batteries for your existing gun
A chest rig/plate carrier/assault vest/belt kit to carry mags, BBs, batteries etc
A hydration system such as a knockoff camelback or a decent water bottle
A pair of sturdy combat gloves?
A set of proper tactical clothing that will last, such as Propper, 5.11 and others
Maybe further down the line a sidearm, holster and mags for it?
Maybe look at GBBRs later on? It's not just about 'not minding' maintenance on them, you also have to have the capability and determination (as well as a steady supply of funds) to keep maintaining one.