Hi Sum
The lump sum is disregarded for 12 months as per the following UC reg:
18.—(1) A payment received within the past 12 months by way of arrears of, or compensation for late payment of—
(a)universal credit;
(b)a benefit abolished by section 33 of the Act; or
(c)a social security benefit which is not included as unearned income under regulation 66(1)(a) or (b).
(2) “Social security benefit” means a benefit under any enactment relating to social security in any part of the United Kingdom [F1and includes armed forces independence payment under the Armed Forces and Reserve Forces (Compensation Scheme) Order 2011].
www.legislation.gov.uk/uksi/2013/376/schedule/10/paragraph/18 Let us know how you get on.
David