Bank holidays have no significance whatsoever in employment law (except for those people actually employed in banking, where the Banking and Financial Dealings Act 1971 applies).
For example (since you work on Fridays) your employer can demand that you work on Christmas Day (which falls on a Friday this year) at your normal rate of pay. There is no statutory entitlement to be given a day off on a public holiday, or to receive any additional benefit for being required to work on a public holiday.
As far as the law is concerned, Easter Monday is 'just another day'. (Exactly the same applies to the other holiday Mondays you've referred to). So, since you don't work (or get paid) on a 'normal' Monday you can't be expected to work (or expect to be paid) on a holiday Monday.
Your only statutory entitlement to paid holidays is to receive 22.4 days per year. (i.e. 5.6 x the number of days you work each week). If your 'holiday year' is calculated from January to December, your statutory entitlement for 2009 is actually 21.6 days because the first three months of the year fell within the 'old' rules (with a multiplier of 4.8 instead of 5.6). The full 22.4 days allowance will apply from next year.
Chris