thanks everyone, sounds like I'm right to stick to the recipe.. even if my friends and family think I'm mad to get up in the night to tend my cheese!
Once I get a bit more confident I might risk leaving it in the press overnight. This would probably mean pressing it for 17 or 18 hours rather than the stated 12. I can't really put it in the press later, as my cheese making window is earlier in the day - later I have a toddler to look after!
And george (MaryJ), nope, not RI, I'm in Wakefield, UK!