Ooh, realised I can get up to 21x21 with one 50km ride around Guildford (well, I only need a 20km ride to cover the bare minimum tiles but no point going there for that short a ride): Marble Arch top right corner, Slough top left, Redhill bottom right, just West of Guildford bottom left. That's next week's ride sorted assuming the trains aren't messed up.
Don't have as much time on a Monday as my daughter's after school gymnastics class has finished (which gave me an extra 1h15m), hopefully she'll want to do it again next term.
Getting to/from places using the trains to do a long enough ride is a bit tighter now and, given how frequent there are problems on the trains, I don't want to be stranded 25 miles away with only 90 minutes to get back. Building up distance though, so should be good for 100km in 5h once the weather improves in Spring, that'll let me cover a lot more ground without worrying about trains at all.