Hi - I'm not in engineering but I've managed to part-fund a very expensive conference trip (to the US for a week) with a mixture of money from my research institute, and from the conference itself. But you supervisor is right - it always looks better if you can get funding from external sources. For example, if you are funded by one of the research councils, they normally offer certain additional funding for travel. I also use (although not sure this applies in your case!!!) the Federation of Women Graduates.