Life / A married impediment certificate - where to get it from? [10]

Hello everbody,Im engaged to a lovely Polish lady.We plan on getting married in a registry office in Poland(Chelm)her home town.I need to get a thing called A married impediment certificate from England to prove i hav'nt been married before.I dont have a clue where to obtain this from,can anybody help me please?

Also i have heard i need to be present when we actually book the date for the wedding at the register office?This is going to be a massive pain the arse if its true,i was there couple of weeks ago but it was a national holiday and the registry office was shut!

Many thanks Scott.