Unions normally negotiate with employers for an annual pay increase, is your union doing this? There does seem to be some improving pay settlements this year, obviously as inflation has taken off, eg around 3%, sometimes with an extra fixed payment so that the lower paid receive a larger percentage.
Then they put the offer to members, sometimes with a recommendation to accept or reject, then if members reject the offer, they'll then ballot the members about industrial action. This may not necessarily be an all out strike straight away, although a few bus driver unions have done this and been out for up to 3 or 4 weeks, before accepting much improved pay offers (around 10% I think).
As for what could happen, it depends how far they want to take it. As an extreme example, the miners were on strike for 364 days (I think possibly there was some legality about the strike not going on for a year, after that time I think the employer may have the right to just sack everyone).
If industrial action is taken, your employer may make an improved pay offer, but from their point of view, they have to make the books balance, which will be difficult especially with the increase in energy costs too.
But as far as the historical pay freeze/1% offer, that sounds common across the public sector, apart from MPs 
and the NHS, nothing apart from a couple of 1%s sounds about right for what has been received amongst the civil service in the last 10 years or so.