You should be able to go abroad for a couple of weeks without it impacting on your PIP.
If you notify the DWP that you have gone on holiday then you may be asked questions about how you managed at a future assessment but I would not expect it, I've never been asked a holiday, although I have not actually been away from home for more than a few days at a time.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems
