There is a current limit of 80 tickets for each Mass/liturgy, and here are the links to obtain tickets (which are available from 17th February) for the various Masses/Liturgies of Holy Week and Easter:
For Palm Sunday 10.30am (only) https://www.eventbrite.co.uk/e/palm-sunday-1030am-mass-tickets-140815680491
For Maundy Thursday https://www.eventbrite.co.uk/e/maundy-thursday-7pm-mass-tickets-140821295285
For the Easter Vigil https://www.eventbrite.co.uk/e/holy-saturday-easter-vigil-7pm-tickets-140822910115
For Easter Day 8.30am (only) https://www.eventbrite.co.uk/e/easter-day-830am-mass-tickets-140823604191
For Easter Day 10.30am (only) https://www.eventbrite.co.uk/e/easter-day-1030am-mass-tickets-140824073595
For Easter Day 12.30pm (only) https://www.eventbrite.co.uk/e/easter-day-mass-at-1230pm-tickets-143083232801 Tickets not available for this Mass until 28th March.
Remember that if you cannot get tickets for any of the three Easter Day Masses (Vigil, 8.30am or 10.30am) that Easter like Christmas is an ‘octave’ and so the following 7 days and 9 Masses all count as Easter Day!