Hi Marykate,
I live in London so am not familiar with the Plymouth area but here are a few observations.
Given the costs involved in buying property for investment purposes, you ought to be looking at a holding period of at least 5 years in my opinion. You will have to pay 3% stamp on this purchase (£12,600) in addition to solicitors fees (another £1,500 or so).
As for capital appreciation - who can tell? UK house prices are increasing at about 5%/6% per annum depending on who you listen to - there was a jump in prices in the early part of this year but the market seemes to have slowed down a little so I would not hold out for a huge amount of capital appreciation unless you are getting the property on the cheap.
Rent of £1,200 p.m. works out at just £300 per bedroom - this appears to me to be fairly cheap given how nice the property sounds - are you sure that this is a realistic rental figure?
How will you be financing this project? How much in cash would you have to put down? The rental yield on £1,200 looks skinny even before stamp and costs etc.
Someone else will have to advise you on the tax side but I know that there is a double taxation agreement between the UK and Ireland.
Johnboy