Please find below response to your queries.
1. How could I protect the idea/concept before I ask any developer to start working on the software?
Basically you can protect your idea, asking the developer to sign an Non-Disclosure, Non-Circumvention & Non-Usage Agreement, it is called NNN agreement. This can help you protect from non-disclosure of the idea & non-usage of the idea aswell.
2. Since my company is in London will I need to have to have it patented in London too?
Patent can be applied for a process & product. Applying for Patent is a complex process, you need to strategize the geographic area where you want to sell your end product.
In India Softwares cannot be patented, may be the process can be patented. However, for Software protection copyright can be applied in India.
3. Once the software is built, does that need to be protected as well?
Yes software should be protected. It can be protected through copyright, trademark, domain name etc.,
Feel free to contact me, if you need further details.
Corporate, Commercial & IP Lawyer
IP Lex Global Services