You can do it yourself. The Bank will return your Deeds to you and the "vacated" Mortgage Deeds. If property is Land Registry - you take it to appropriate Land Registry Office and they will help you fill out the form 17.
If property is Registry of Deeds, you go there - Constitution Hill. Again, they'll help.
You do not really need to register the Vacated Mortgage - that can be done at any stage. However, like most things, do it now or it will get lost.
You have to work out what to do with your Title Deeds. Older Land Registry properties with no planning permissions and only a Folio are simple - just get a copy of your folio from the Land Registry. Newer properties and older properties with a Registry of Deeds title will have a bundle of important Title documents that will always be needed when selling and they should be kept in a safe place -preferably with a Bank or similar. Solicitors and most Banks do not like keeping Deeds - they are a risk - if you lose them, you have a responsibility.
You could ask your own bank if they will hold them for you.
mf