NP Puddle

Hi. I am non resident and return to the uk once a year to check rental properties. I have never claimed expenses associated with these trips previously but now understand these are allowable expenses. I will claim the costs for my 2023/2024 trip on my next return but can you advise me on the process to claim any previous years trips and how many previous years I can claim for. I have tried ringing many many times but the helplines are either not in use or I get cut off. Thank you