Yes you can claim the cost of the furniture at the rate of 12.5% over 8 years. This does not come under the pre letting expenses rule.
As many of you are new to doing this and seem to be doing your accounts yourself, if you have any doubt, then just enclose a letter to revenue stating that
'I have deduced x amount on y because z and I'm not sure this is correct. '
Send this and your return by registered post, or get revenue to stamp a copy for you if you drop it off and keep a copy of everything. In most cases revenue don't reply as they 'agree' with what you have done so that's the end of the matter but you need the letter in case there is ever an audit /query later on by revenue.
The cost of accounts done properly by a professional in the first year is to be HIGHLY recommended based on the questions posed by so may first time renters. As is reading the form on letting and other websites.