I have not tried this, as I've never been in a situation with such limited instructional time, but here's how I might approach this.
I think I'd have to utilize a lot of role-playing to practice dialogue. With only eight hours, you're going to have to rely heavily on memorizing set phrases for certain situations. You also won't have much time to spend focusing on grammar explanations or exercises - just tell them what to say, and as time allows, some possible variations to use and expect.
Granted, that's not an ideal approach, because if a customer deviates from the script you practice in class, your students will likely be thrown for a loop, but in that time frame it's just not going to be feasible to practice many variations.
After meeting with HR and discovering what roles these students will be in (i.e. housekeeping, maintenance, kitchen, reception, bellhops, etc.) pick 6 or 7 situations (one for each weekly lesson) they'll likely encounter when interacting with guests in that role, and then design some dialogues for role playing. Finally, have students act out the roles of both guests and employees. Anybody interacting with guests will have a lot of numbers thrown at them, so work a lot of telephone numbers, room numbers, addresses, and dollar (or for you I guess it would be pounds and possibly euros) into the dialogues.
If you're really lucky, all your students will be of the same occupation, and you can spend more time practicing additional scenarios within that role, but more likely you'll get a mix of hotel jobs and have to try blending different job scenarios in a given hour.
I'd divide the hour up into three or four segments (this will depend upon how many different scenarios you need to cover per lesson). Spend 5-10 minutes of each segment pre-teaching vocabulary and troubleshooting major pronunciation issues, then dive into role play and speaking for the rest of the segment. Model everything first, of course. Switch segments every 15-20 minutes. You might be able to break them up by occupation and have multiple groups working at once, although that become difficult to monitor.
Reserve one session (probably the first) for teaching greetings, introductions, general questions (what seems to be the problem, how can I help you, etc.), and just trying to get a feel for individual levels. I'm certain you'll discover that the expression "Basic English" has a LOT of leeway and variance as to what your students actually understand. 'Basic' might be nothing more than numbers and colors....
Alternately, if some of the students won't be interacting with guests, but rather just with their respective supervisors, focus more on vocabulary and commands they're likely to hear. In this case, I'd move off the dialogues some and focus more on role play where you're actually doing some of the tasks. Have some towels to fold, dishes to wash, etc. as you give commands. Practice isolated commands first, then move to a kind of 'Simon Says' where you throw varying commands at them one after the other.
Props will be your friend for either of the approaches -you'll be relying heavily on the concepts of Total Physical Response. Have them touching things they're talking about and physically doing the various actions. Depending on the role being played (based on their actual job), they may need to practice writing down some things they hear.
Perhaps HR could request supervisors to come up with a short list of their most common instructions to assist you?
I hope this helps a bit. It's mostly just a stream-of-consciousness approach, because as I said earlier, I've never actually had to try my hand at your exact situation.
I agree with Piscean that you've been handed a tough row to hoe. Good luck. Let us know how it goes.
