Helmet, lights, a decent set of road shoes with clips and unfortunately Lycra. invest in the best bib shorts you can. £50-80 will get you a good pair. A decent long sleeve, short sleeve and base layer jersey(wiggle DHB stuff is great) then just get out and enjoy, aim for 15-16 mph and start with your rides, set yourself a monthly distance /time goal. It will be hard. It won’t ever get easier, you will just get faster.
I was happy for bike advice, but if having a tough time, then I fully advocate it’s ability to help you get away and feel better
Depends on what you want but I'm also looking at getting something to make the commute (when allowed!) a bit more of a breeze and also be able to go on rides with my mates that have faster bikes. ive got a very heavy workhorse mountain bike at the mo I bought off a forest hire place. I think I'm going to go for a gravel bike which gives me a bit of both. Good on the road but will allow me to go off piste when needed.
