Where abouts in Truro are you? Can you get yourself down to the Pottery Playgroup, Monday, .wednesday, Friday 9-10.30. Sophie who runs it is lovely tell her .rachel sent you, she rescued me in a similar situation a few years ago!
Lovely group, lovely mums, in fact PM me to let me know when you might be going and I will have someone look out for you!
Sadly mine are well into school age now so I don't pop,in that often!
I would recommend getting the train to falmouth docks one day if its sunny, a small walk to castle beach which is v young toddler friendly.
3 local Truro parks, all lovely, safe, and with room enough for a picnic!
PM me if you need anything else, a good hairdresser... The best pasty in town, what do do on a wet Sunday, that kind of thing :-)