8.33 will probably start migrating slowly across the world so if you're getting something to last 10+ years then I'd go for one with it.
Get something with a headset adapter. Different models need different adapters.
The SP-400 from Sporty's includes an ILS view along with VOR - up to you whether you'd find that useful (how long does the GPS battery last?). Difficult to buy within the UK but you might be fine. It also runs on normal AA batteries. I'm thinking about a purchase myself...
If you're going to be using it for listening in to others while on the ground, think about some way to plug it in (although not necessarily a desk stand). You may have a suitable transformer / cable already but they do eat batteries. Older ICOMs use a large NiCd battery which has all the normal Nickel Cadmium characteristics (drain over time, memory effect, large for the capacity), so worth checking and making sure what you're looking at uses a more modern technology.
However - during training you really don't need one. Talk to your instructor about what to do in the event of a radio failure. Many airports have radio failure procedures anyway (such as orbiting at a specific point at the edge of, or even within controlled airspace, or use of a mobile phone...). BTW - don't expect a mobile phone to work above 1500 feet. You might be lucky (or you may have to orbit to keep a consistent signal) or you might not be...