With regards to training for the Ring of Kerry in July, February is the Month when you should be concerned with slowly beginning to extend your mileage and build on the level of fitness that you have already. For this month I would advise at least two session on the bike per week (preferably three) and two other sessions of strength/flexibility work which can either be done at the gym or at home.
It will depend upon your schedule and commitments but hopefully you have time for at least two good spins a week. What I mean by good at this time of year is a 1-2 hour cycle. The approach for these cycles should be about building a good base of mileage and you should no be beginning to pick more demanding routes with varies terrain and inclusive of some elements of climbing and keeping a good cadence (80-100 rpm) throughout the spin.
The other two sessions in the week can be of your choosing whether you like a fast walk, a swim or a session in the gym. Whatever you so though make sure to allow some time for stretches and exercises that strengthen your back and abdomen muscles which will give you a strong core and improve your posture on the bike particularly on longer spins. Good luck for the month and be consistent!