For an 8/9 year old gnarly 'ripper' you got a couple of options I'd say, Mouldy Boots. There isn't really such thing as a beginners board unfortunately.
1) A penny board - they're small and a lot of kids seem to ride these and good if they just want to cruise around and not do any tricks - they...
Speaking as a planner who, until recently, worked for a local authority in Sussex - I'd advise you apply for retrospective planning permission if you've already replaced timber framed windows with UPVC. Permitted developments rights do not apply to flats, although windows could be replaced...