Can work change my shift pattern without any notice?

I was suspended on full pay due to allegation made about my by a client now Iv been cleared of allegation I am being asked to return to work but to another site and on a different pattern meaning it now throws plans iv made up in the air such as my annual holidays and a weekend iv got coming up were Im away in spain they will now have me on shift for that weekend, Iv not actually been told of the change yet but colleagues have contacted me to tell me of the change which Im expecting tomorrow by phone, even if they honour y time off it still leaves me having to loose pay days.