Lexus are (is?) (reasonably) a low number manufacturer, and only when you order your car does the building process start. Obviously the waiting time is then several months, although there may be a dealer somewhere in the UK who has the model in the colour and with the specs you want and your local franchise can order it in.
A car bought this way will be a 2024 model, whereas the 2025 models will available to order quite soon (with a price rise)
On the other hand, if you are spending 40 to 50k (or more) then saving a few thousand over five years shouldn't be a priority compared to getting the correct specifications.