How to tell your supervisor at home university you are accepting an offer somewhere else?

[OrpheusGaze]

So, I'm a Master's student in the UK and I'm a bit in a rut on how best (i.e., politely but honestly) to tell my current professor/supervisor that I will be turning down a PhD funding offer from my home university in favour of another offer somewhere else in the UK. 

I have been working with two professors from my department on my research project since October. They have gone over and beyond with the help they have given me over these past few months  - proposal tweaks, funding applications, and so on. They also know I have applied to another university apart from the one where I am currently based, especially since they wrote letters of recommendation for me, so this is not really a surprise. 

About a month ago I received a funding offer from the other university and I decided to accept it provisionally, though I also chose to keep it for myself until I found out the outcome from two funding applications related to my home uni. Last week the result of the first funding application came through, and I was amongst the awardees. My professors emailed me very enthusiastically and told me that the outcome from the other application was due next week, but that no matter what the latter is going to be, I have already secured funding and should not worry anymore. 

Right now I am waiting to hear back from my last funding application at my home uni. I have been poring over my choices over the past week, and I have decided (for a variety of reasons, both personal and academic) that I would like to move to the other university. I still haven't notified my professors, and I am not sure as to the best way of doing so. Should I wait until this Monday, find out what the outcome of the last application at my home uni is, and then tell my professors that, with all options on the table, I'm going to take a few days to think about it? Or should I just rip the band-aid on Monday?

I realise this probably sounds like a non-problem, but I have a really good relationship with my professor and they are (or at least seem to me?) very invested in this project. Besides, I'm a bit clumsy when it comes to social interaction to begin with. I'm beginning to think that maybe it might have been a better idea to inform them about my offer from the other university as soon as I found out last month, instead of waiting it out. I'll be sending a thank you card and a present as a token of gratitude, but I'd be curious to know what you think is the best way to tell them in the first place... 

[Sigaba]

 If they're true professionals, they'll understand that the way you handled things is the way you wanted to handle things and their opinions won't get in the way of how they treat you professionally. Even so, I recommend that you understand that even if the two professors respond in a polite and professional manner, either may see your decision making process in an unfavorable, if not unflattering light. From your perspective, the risks of fuller  disclosure apparently outweighed the benefits. A potential qualifier would if both professors were aware of the personal and academic reasons you would want to move on.

Tactically, I recommend that wait until you hear back from your home uni, let them know you have options, and that you're going to think things through. 

I would think twice about giving the professors gifts -- a brief, heartfelt thank you note will suffice. Down the line, when you're an established academic, you can pay for a round of drinks or a meal at a conference.