I cut out gluten and dairy last year and felt great after having low-level stomach ache every day for the last 20 years! Cutting both out was very tricky (and expensive!) but now I just avoid lactose and feel a lot better for it.
Lidl sell lactose-free milk cartons and I buy Arla lactose-free cheese (red packet, about £2.50 a block from Sainsbury's). I also have oat milk in coffee.
Oatly sell a nice creme fraiche too, and a cream alternative - Sainbury's sell both.
I started making ricotta which is really simple. You just bring full-fat lactose-free milk to the boil, add herbs if you like them, turn off the heat, then add lemon juice until the curds and whey separate, then drain most of the liquid away. I use a muslin cloth in a colander and give it a gentle squeeze. It sounds fiddly but is really easy once you've tried it!
I really miss mozzarella, brie, goat's cheese, and chocolate, but I'd take a limited choice over the daily stomach ache/upset any day!
For a treat I have dark chocolate now. That took a while to get used to but I look forward to it now.
Someone recommended lactase tablets to me so you can eat lactose and the tablets break it down in your stomach. I bought some from Boots and they're a bit hit and miss (I seem to have to take them exactly 20 minutes before eating, any sooner or later and they don't work) but worth a try if you don't want to cut out certain foods.
Good luck!