Pzu, I would expect a 0530 arrival to be fairly safe!
From the Border Agency website:-
Advice for customers
The 4 Home Office unions are participating in a strike which will affect border control from the beginning of the evening of Tuesday 29 November until 23:59 on Wednesday 30 November. Starting times will vary as each port has different shift patterns.
We will aim to keep disruption at a minimum, but our priority remains the security of the border and we could see longer waiting times at some ports and airports. We have put contingency plans in place and will work hard to keep delays to a minimum.
You may wish to check with your carrier if you are travelling on Wednesday 30 November.
Passengers arriving in the UK can assist us by:
having travel documents, including passports, available and taken out of any wallets;
using automatic e-passport gates (where available);
having landing cards fully completed and ready; and
staying in family groups.