Starting to buy your own dive equipment

[Vitesse2l]

Zoop Novo will be fine to get going and for quite a while after. Make sure to read the manual several times! It's display isn't intuitive I find, and mine defaults to a temp display bottom right of main screen. A single button push gets it to show elapsed time instead, but you dont want to be fiddling with buttons looking for a function. Enjoy your dive holiday!

 

[Must_dash]

Mike's dive store is in London (Chiswick) whereas Simply Scuba is a fair distance from London in Faversham, Kent. So on that basis alone I'd recommended Mike's over SS.
I haven't visited Simply Scuba but have been to Mike's a couple of times. They have a very good range of stock and the staff are knowledgeable (most, if not all, are divers). They can get very busy so you may want to bear that in mind - maybe avoid the weekend if you can.
Ocean Leisure in central London may also be worth a. visit... Ocean Leisure - London’s premier marine & water sports super store

We're flying to Gatwick so train or car isn't a problem. Looking for advice and being able to walk away with kit rather than them ordering in for us.

 

[UFOrb]

We're flying to Gatwick so train or car isn't a problem. Looking for advice and being able to walk away with kit rather than them ordering in for us.

Fair enough. Then Simply Scuba is a fairly straightforward drive from Gatwick - should be around 1-1.5 hours drive, depending on traffic.
I guess it's a case of checking which shop has the gear in stock that you're interested in then! Good luck with your mission