I am not sure what exactly 'PVA' glue, is, I think it is white paste glue IIRC... but no, I don't think you can. Envirotex is a specialty product used as a lacquer substitute, I think 1 layer of Envirotex is equal to 7 coats of lacquer... or something like that.
I am pretty sure you can get it in the UK, it should be a common hobby supply. I recently found it in a local hobby shop, which seems to have a lot of nothing (stuff I don't need), but they did have Envirotex.
Also, search google about trees. A friend of mind has used some sort of small shrub twig, painted it brown, and put torn up scotchbrite pad fibers all over it to make decidious looking trees, and with some extra detail, they could look pretty realistic.
note: I didnt even notice the baby in the corner of the pic untill my girlfriend noticed it at a glance.