Mondie
Tell your IP about it, it shouldn't count as a "windfall" which you would normally have to hand over into the pot, as it's compensation for the loss of your job, however, were you to obtain another job quickly, then your IP may feel that some sort of additional lump sum payment should go into the IVA. In the meantime, put the money into a savings account and don't be tempted to spend it all.
The remaining 34 payments you have to make total £11,866, which is less than your settlement, but if you were to offer that to clear your IVA immediately upon your redundancy, it won't leave you much to live on until you get another job. AT least it looks like you'll be given plenty of notice to look for another job.