If there are alternatives for £170 - £180 then as per my original post, I did indeed drop a bollock. I hadn't realised at the time that Frankfurt Hahn wasn't actually in Frankfurt. More research needed next time. The FR flight was as near as makes no difference £100 all in with hold baggage. I've booked a shuttle from the airport to the city now which makes the whole thing around £100 cheaper overall with FR. Not my finest hour but we all make mistakes I guess.
I would also say that the Ryan Air flight was quite convenient for us time wise.