Finally changed my tyres and inner-tubes over today and whilst doing so managed to fix the rubbing sound in my rear-wheel so quite please about that and saved a trip to the LBS. Although they weren't the easiest tyres in the world to put on, they've made all the difference in terms of rolling resistance.
Afterwards, I met a friend and we took ourselves off for a good 25 mile bike-ride which is the longest ride I've done in over ten years. The bike held up very well, although my arse not so much. Could've happily managed the return journey but got the train instead. Sitting down did not help as when I got in after riding back from the station, my legs really did not like me. Only thing of concern is that I'm going to need new grips as they're already fraying and my front suspension - not sure if this is normal? - squeaks a little oddly when the rebound is set medium to high and is rebounding after compression.
London-Southend next month. 57 miles. A little less concerned about the distance now, but still going to be tiring. Should be interesting though, far more people doing it.