Wanting to downloads maps of ireland and england can i do this how much does it cost?

Yes there is a map of the UK and Ireland available from https://buy.garmin.com/shop/shop.do?pID=8424&pvID=30136 which can be downloaded or bought on an SD card at a cost of £36.99 which is compatible with your satnav.

It will depend on how much memory you have in your Garmin. If you have maps that you want to keep then I would download those first and then add in the Ireland maps. Or wait until you leave to add in Ireland. I believe the Garmin will tell you if there isn't enough room to add in Ireland.

The 730, unlike the 930, doesn't come with European maps preloaded. You can find the most up to date Tele Atlas maps of the UK & Europe over at TomTom's Map Store.