Accommodation rules help - do I need to move for SV?

[spousevisahelp]

I am planning to travel to New Zealand to marry my partner so that he can apply for a spouse visa to join me in the UK. I have a good job and he previously worked in the UK in a similar job (WHMV) so there are no problems with the financial aspects but I am concerned about accommodation. At present I am living in a shared house with 3 other women (one bedroom each). I am sure they and the landlord will not give permission for a 5th person to live in the house so I am facing moving for the spouse visa. Do I definitely have to provide proof that I already have accommodation available as we will want to find somewhere together after he arrives, is working and we can afford to rent a 1 bedroom flat.

I do not have any relatives to stay with and rent in London is expensive so I would rather avoid having to rent somewhere large enough for 2 people prior to making the application at the same time as paying for a plane ticket to NZ. I realise getting in a room in a shared house could be difficult as landlords and housemates would be reluctant to accept a person is going to be living in the house that they haven't met. Am I faced with having to find a double bedsit or studio at high cost and get the landlord to write a letter saying that he will be able to live there after our marriage (again difficult when they haven't met him) in order to meet the arrangements?

Getting married overseas seems cheaper than doing the fiance/marry in UK/spouse visa in UK option but is there no way around the accommodation problem?