I don't think its illegal either POH outstanding in the UK.
If you haven't flown in the RHS before its worth while having some circuits with someone that knows what they are doing before going flying.
I don't know what instruments you have on the RHS but IFR looking across is a whole different ball game with parallax error etc.
You really need though to find out what the rules are though for each country you intend to fly in. I don't have a clue what the rules are in France and Spain or for that matter if the rules are going to change with the EASA stuff.