^^ that’s a good alternative.
We have two on the farm, no need for planning permission.. You are going to need to check your local BC to see if you need one where you intend to put it.
We spent 7mths locating some seriously good ones, we found some American spec double lined (intended for fragile goods) cost £1800 ea.
We then vented them and built them out with Rock Fibreboard to make them both quiet and damp proof. We stuck a roof on and insulated it, then bridges between both with a sloping roof.
During the build, we partitioned one off for secure storage.
Ours a very strongly built, have lots of secure hinges and stuff.. but tbh if someone wants to get in, they don’t have to try too hard.
Build a more secure shed is my take from all the hard work we put in.. they’re good but..