Combining lookup and forecast formulas

Hi, <for the background to this see my previous posts!>

I have cracked the initial problem of doing multiple lookups/interpolations from a matrix at the same time (i.e lookup 5 parameters). now I want to combine the formula's into one really long one - so I can have the answer in one cell and then work on time series instead of indivdual points

I basically want to combine these equations (actually I want to combine lots more, but if someone can tell me how to combine these I'll do the rest!)

(in cell c18) =VLOOKUP(Front!A18,s4_1!$A$2:$L$2065,9,TRUE)
(in cell c19) =VLOOKUP(Front!A19,s4_1!$A$2:$L$2065,9,TRUE)

(in cell g19) =FORECAST($C$4,C18:C19,$F$14:$F$15)

(in c20) =VLOOKUP(Front!A20,s4_1!$A$2:$L$2065,9,TRUE)
(in c21) =VLOOKUP(Front!A21,s4_1!$A$2:$L$2065,9,TRUE)

(in cell g20) =FORECAST($C$4,C20:C21,$F$14:$F$15)

(in cell k21) =FORECAST($C$5,G19:G20,$G$14:$G$15)

Can these all be combined into one cell?

Here's an example spreadsheet and a description below:

In "Front" is the working at the input values and the values I want.

c4:c9 are the values to lookup
in d4:d9 are references I get by looking up the values up in I want (in c4:c9) in the array h3:011 i.e a,b,c, - these are the references for the lower values to interpolate from.
In e4:e9 are references I get by looking up the values up in I want (in c4:c9) in the array h3:011 i.e a,b,c, - these are the references for the higher values to interpolate from.

In F14:K15 I have the values based on these references

IN A18:A49 are the references concatenated, I use these to lookup the values for c18:e49 in the s4_1 sheet.
b18:b49 are my check cells these are my references for example A1,B1,C1,D0,E1, C1 means the higher value for Offshore waveheight and A0 means the lower value for nearshore height - these just allow me to check my results easier.

Sheet s4_1 is the matrix array.

Still with me?

Thanks