The project to build a five-storey extension is estimated to be worth up to £18m and has been scaled down from a more ambitious earlier plan for a £26m project and retendered.
Phase 3b of the expansion plan will also include alterations to an adjacent conference centre, relocation of the existing car park to create a 180 space new car park and creation of a new landscaped public area.
Interested firms have until 7 December to complete the prequalification process and can contact Barbara Tsang, tel 02476151049 or use the tendering portal.
