An Annual inspection on a AA5 is no big deal, like the 50 hour check it is well within the abilities of most technically competent pilots.
However first you need to be confident to undertake the work and get your hands dirty. Have a look at owners permitted maintenance tasks in Annex VIII.
Second you need to be able to work in your aircraft's hangar. Incredibly some airfield owners prohibit maintenance work by residents on their own aircraft.
Thirdly you should have a copy of (and thoroughly understand) the aircraft manufacturers maintenance programme. Failing that one of the ludicrous CAA generic programmes ... LAMs LAMP or one of the made up programmes cobbled together by the part F & G organisation. The manufacturers programme is the one to use as it gives specific tasks on specific items. You then need to operate your aircraft out of the controlled environment. That means you become your own CAMO and take responsibility for the continuing airworthiness of your aircraft ... ADs, service checks, time expired items, etc. Not a task for the faint hearted. One or two owners maintenance tasks may not be permitted under appendix VIII and these can be done by your local maintenance organisation. But you have to establish who is boss. You are requiring the engineers to carry out a specific job ... no more and no less ... and they must give you a time and cost estimate for the work. Also you are their client and you must check that they have carried out the work to your satisfaction. If you have been in the habit of giving your aircraft to the engineers and leaving them to do as much or as little work as they see fit, then for sure you are going to be ripped off. Sadly few UK pilots really understand EASA part M, and still assume it works like the old CAA system. There is a good chance that a less onerous maintenance system called part M light may appear soon, but EASA aircraft will most probably still need an ARC every three years or annually if out of the controlled environment. In short you can save money if you do it yourself but there is quite a lot of hassle and you will spend more time doing paperwork and spannerwork than flying.