For radios themselves lots of people will recommend baofengs uv5r which can be good and can be good for starter or Airsoft radios.
However, to use them you should have a license and when people get the licenses they tend to go for the small business licence (£75 for 5 years) and covers a group of people. Some sites (gunman Airsoft for example) and allow customers to use their licence/channels. Lots of people don't bother to get a license and I have never heard of anyone being caught, but that's the law bit covered.
You shouldn't use them on pmr channels (too powerful) but you'll have channels you can use them on
They take the standard Motorola or kenwood (can't remember)fittings, so you could get a standard speaker mic for them and a covert ear piece. Or you could go to someone like JCI Comms and get a military style ptt which would mean you can plug them into your military style headset. Going this way is expensive, but good Comms are expensive. There are issues mixing and matching repro comm stuff with real stuff, JCI can recommend.
You could also go for standard pmr radios from Argos, but most won't be powerful enough for some sites (especially with buildings). And headsets etc will be more limited.
Next up you could go for Motorola, kenwood or yaesu. They're the next level and most will need licenses. Similar issues as with baofengs on the accessories department but the QC on the handsets it better. Baofengs have a habit of failing when they are exposed to damp, I used then for weekend events and after binning off my 4th or 5th one I got a Kenwood and have used it since, £25 per baofeng or £175 for a Kenwood. I was using it for a lot of weekend events, in the rain, cold, snow, hot etc.
If you really want to pay out but have what should be amazing comms, you could get a TCA or Tri 148/152, basically repros of real radios, £250+ for the radio + only works with legit ptts and headsets. JCI Comms (Facebook and instagram) will be your friend here. From what I've seen they're amazing when they work but often have issues or niggles.
For you, my recommendation would be a baofeng uv5r, a baofeng speaker mic and a covert ear piece from eBay, roughly £45 all in, plus your license if you need one (depending on your site). It works for most airsofters needs 95% of the time. If you really enjoy them etc, then upgrading when you're more knowledgeable is sensible.
I don't know about blue tooth for the foregrip based ptts, sounds good but risky Vs hardwired
