Don't worry miffy - there are plenty of Ab'ers who can answer sensibly and have so much knowledge to offer (I'm not one of them sadly but I do know a bit about employment law).
Unfortunately, there is nothing you can really do other than speak with your boss and explain the laws regarding part-time staff being treated the same as full-time. Tell him that you know it doesn't apply to you, as he doesn't have full-time staff, but you are a loyal employee and plan to stay working for him for the forseeable future and would he consider coming to some arrangement so that you don't feel disadvantaged through working for him rather than a larger company employing more staff. Obviously, this depends on the kind of working relationship you have and it may not work - but at least you would have tried!
Good luck :o)