Don’t know that there is much up the north coast, stick a wee post on mtbrider and ask, davagh (cookstown) is being made into a trail centre but has decent existing trails.
If your heading south, tollymore forest park is great (Newcastle) depending on which day you free I could show you around there.
As said before bigwood is running well at the mo, all good natural trails in quite a small area.
There is a large get together there on the Sunday after Christmas you could tag along with