Have you started any training at all yet? If not, don't run before you can walk! Your PPL exams will warm you up nicely to get stuck in to the ATPLs. So, perhaps start watching some online youtube videos on PPL theory or pick up some PPL theory books to get yourself pointing in the right direction. Also, more important than anything, if you haven't got a class one medical from the UK CAA yet, then do that ABSOLUTELY before you spend a penny on anything else. No point spending a few grand and then realising you can't get a class one and thus never ever be a commercial pilot. Class one medical first. Will cost around £700 for an initial medical then £2-300 per year there after.