One thing to note is the Open Source software, in guidance handed to all government departments, should be preferred over proprietary software. (link in here somewhere http://www.oss4gov.org/policy_activism)
In addition the "G-Cloud" - a online catalog of pre-vetted service providers, has 80% SMEs on it and a govt buyer can simply sign up online for a Saas service there and then with a govt credit card, legally
I feel that Open Source in government will have serious network effects globally, so getting this right now for the UK could lead to a very long tail / virtuous circle for UK devs in the future.